What is a Surge Tank?

[Lindenberg]

What is the purpose of the surge tank for the cooling system do on our Alpines? I do know it is not a coolant recovery tank.

And finally, do you check the coolant level through the sight glass when the engine is cold or hot?

[Lindenberg]

What is the purpose of the surge tank for the cooling system do on our Alpines? I do know it is not a coolant recovery tank.

And finally, do you check the coolant level through the sight glass when the engine is cold or hot?

[Dave Fernandez]

Hello Tom:

The surge tank is used on vehicles when the radiator is lower than the top of the water jacket on the engine so air bubbles do not form in the cooling system. I check my water level when the engine is cool. If the level is below the sight glass I have even removed it and checked to see how low. I also look at it when the engine is hot and if it over the sight glass I do not worry.

[Mike & Mike]

I remember an excellent comment here on the forum a few months back. Someone had a tank that was mounted at a slight angle and it always "apparently" had green antifreeze in the viewing window. That was only because there was always this half-teaspoon of fluid that never went away due to the angle. I checked mine and have the same problem so I never trust the window.

So, do not assume that fluid in the window means that much fluid in the tank.

Cheers!

[OldForester]

On our '06 I learned that I needed to check the sight glass with the engine running, but not up to operating temperature. If I filled it up to the middle of the sight glass window when shut off and cold, it would overflow for a while, a few drops at a time when running. But if it was running and cool, and in the middle of the sight glass window, it would fill the window when hot, but not overflow.

[dgerstel]

I found my coach did the same as OldForester's. I wanted to check when the level when cold and not running, so I just added a coolant recovery tank. Easy, cheap job and now I just set/check level when cold. Tank catches overflow and replenishes level when the engine cools off.

Dale